(Maybe I'm wrong), in the listing of the Dead Sea scrolls fragments Megillat Ester is missing. That seems strange taking into the account that the Megillah says that memory will never fade away.
The list does include Ruth or Job or Song of Song. Also, the Megillah does not seem to be exclusively related to the Pharisees to claim that others didn't accept Purim.
The Mishna in the Megillah tractate was composed (as the rest of it) long after the destruction of the Temple. On the other hand, the Mishnah describes nicely how Succos was celebrated in the Temple, or Yom Kippur. But how Purim was celebrated in that era?
What sources describe celebrating Purim during the Second Temple era?
Also, are there external testimonies on the Jews celebrating Purim abroad, in the Assyrian or Roman empires?